With the recent improvement in operation speed and image quality, and the reduction in production cost of recording devices such as a printer, a word-processing machine, a facsimile machine, or the like, many of the recording devices employ an ink jet recording method. Typically, the ink jet head employed in such an ink jet recording device has nozzles from which ink droplets are jetted toward a recording medium such as a sheet of paper on which these ink droplets land to effect printing.
Incidentally, if water repellency at a portion surrounding a nozzle orifice of the nozzle member is insufficient, this will cause the ink to readily adhere to the surrounding portion. If ink adheres to a portion surrounding a nozzle orifice, this will reduce the linearity in travel direction of ink droplets jetted from that nozzle orifice. It is therefore difficult to effect satisfactory printing. To cope with such a problem, a water repellent film is usually formed on the surface of a nozzle member, as disclosed in, for example, Japanese Unexamined Patent Gazette No. H06-87216.
Water repellent films which are formed on the surface of nozzle members are roughly divided, by formation method, into two types, namely water repellent films of the application type and plasma polymerization films. The application-type water repellent film is a film formed by application of a water repellent material on the surface of a nozzle member by dipping, spray-coating, or spin-coating. On the other hand, the plasma polymerization film is a film formed by plasma polymerization.
Generally, in a typical ink jet head, cleaning including wiping of ink adhered to the surface of a nozzle member is carried out at regular intervals. However, although the film thickness of conventional water repellent films of the application type is not thin at all, these water repellent films readily come to peel off and are poor in abrasion resistance. In other words, wiping causes such a conventional water repellent film to readily peel off and wear out. For this reason, it is difficult to maintain water repellency over a long period. Accordingly, in order to improve abrasion resistance, the film thickness may be increased to a further extent. However, if the film thickness is too thick, this will result in distortion in film shape when nozzle orifices are formed and sagging in the vicinity of the nozzle orifices. Due to such drawbacks, the state of jetting ink droplets is likely to become unstable.
Conversely, the film thickness formable by plasma polymerization is just 10 nm at most, so that plasma polymerization films are likely to be poor in abrasion resistance because of their thinness. Moreover, since the degree of adhesion between the film and the base material (i.e., the nozzle member) is generally poor, it is required to provide an adhesive layer, such as an inorganic film, between them in order to improve the degree of adhesion. Furthermore, the plasma polymerization requires the provision of vacuum equipment. Moreover, the plasma polymerization requires a greater number of process steps for the formation of water repellent films. As a result, the cost of equipment increases considerably.
Bearing in mind the above-described points, the present invention was made. Accordingly, an object of the present invention is to provide an ink jet head in which a water repellent thin film, which is less readily peelable, superior in abrasion resistance, and capable of easily making the state of jetting ink droplets stable, is formed and to provide a method for the manufacture thereof.